Neurally adjusted ventilatory assist versus pressure support ventilation: a randomized controlled feasibility trial performed in patients at risk of prolonged mechanical ventilation

Abstract

Background: The clinical effectiveness of neurally adjusted ventilatory assist (NAVA) has yet to be demonstrated, and preliminary studies are required. The study aim was to assess the feasibility of a randomized controlled trial (RCT) of NAVA versus pressure support ventilation (PSV) in critically ill adults at risk of prolonged mechanical ventilation (MV). Methods: An open-label, parallel, feasibility RCT (n = 78) in four ICUs of one university-affiliated hospital. The primary outcome was mode adherence (percentage of time adherent to assigned mode), and protocol compliance (binary-≥ 65% mode adherence). Secondary exploratory outcomes included ventilator-free days (VFDs), sedation, and mortality. Results: In the 72 participants who commenced weaning, median (95% CI) mode adherence was 83.1% (64.0-97.1%) and 100% (100-100%), and protocol compliance was 66.7% (50.3-80.0%) and 100% (89.0-100.0%) in the NAVA and PSV groups respectively. Secondary outcomes indicated more VFDs to D28 (median difference 3.0 days, 95% CI 0.0-11.0; p = 0.04) and fewer in-hospital deaths (relative risk 0.5, 95% CI 0.2-0.9; p = 0.032) for NAVA. Although overall sedation was similar, Richmond Agitation and Sedation Scale (RASS) scores were closer to zero in NAVA compared to PSV (p = 0.020). No significant differences were observed in duration of MV, ICU or hospital stay, or ICU, D28, and D90 mortality. Conclusions: This feasibility trial demonstrated good adherence to assigned ventilation mode and the ability to meet a priori protocol compliance criteria. Exploratory outcomes suggest some clinical benefit for NAVA compared to PSV. Clinical effectiveness trials of NAVA are potentially feasible and warranted.

Neurally adjusted ventilatory assist in acute respiratory failure: a randomized controlled trial

“…Since all that is set during NAVA is the proportion of effort provided by the ventilator to supplement the patient's ventilatory drive, for a given NAVA level, the airway pressure varies breath-by-breath in proportion to Edi. Three randomized controlled trials on NAVA have been previously published [9,11,12]. Demoule et al [9] randomized 128 patients ready for partial ventilatory support to NAVA or pressure support.…”

“…NAVA did not affect mortality. Hadfield et al [11] randomized 78 patients at risk for prolonged MV to receive NAVA or pressure support. They found that NAVA was associated with more VFDs, however, no significant differences were observed in duration of MV, ICU or hospital stay.…”

“…Clinicians have a hard time identifying the presence of asynchrony at the bedside [7] despite that numerous ineffective triggering has been associated with increased duration of mechanical ventilation [8]. Previous trials comparing pressure support ventilation with NAVA [1,[9][10][11][12] did not provide sufficient evidence for duration of MV or survival benefits in patients with ARF. We hypothesized that NAVA compared to conventional lung-protective MV would improve patient-ventilator interaction by making the transition to spontaneous breathing much quicker and easier, and would result in an increase of VFDs, a decrease in ventilator-associated complications, and in a better survival.…”

Proportional modes of ventilation: technology to assist physiology

“…In that study, NAVA reduced patient-ventilator asynchrony and the rate of post-extubation application of non-invasive ventilation, and feasibility and safety of NAVA over several days was successfully demonstrated. A recent study confirmed acceptable adherence to the assigned mode beyond 48 h when comparing NAVA with PSV [ 21 ]. Furthermore, Liu et al recently showed shorter weaning duration with NAVA compared to PSV in selected difficult-to-wean patients [ 20 ].…”

“…Moreover, safe targets for respiratory effort may vary among patients, depending on the severity of lung injury and diaphragm function [ 15 – 17 ]. The uncertainty regarding titration of inspiratory support with NAVA and PAV+ might be one of the reasons why there is still limited data showing improved clinical outcomes when using proportional modes as compared to conventional modes [ 18 , 19 ], but clinical benefits of NAVA compared to PSV were recently demonstrated in difficult-to-wean patients [ 20 , 21 ]. At the same time, despite having very complex physiological consequences, PSV maintains an appearance of simplicity and is the most frequently used partially supported mode of ventilation [ 22 ].…”